| covariate | Estimate | SE | P-Value |
| (Intercept) | 1.936 | 0.267 | 0.0000 |
| Z1 | 0.671 | 0.267 | 0.012* |
| Z2 | −0.021 | 0.268 | 0.939 |
| Z3 | 0.427 | 0.285 | 0.134 |
| d | −0.127 | 0.0006 | <0.000001 |